Vein bypass grafting is a mainstay of therapy for patients with atherosclerotic occlusive diseases of the coronary and peripheral circulations. Failure of vein grafts, ultimately resulting in thrombotic occlusion, incurs significant morbidity and mortality as well as the need for costly reinterventions. The development of gene transfer technology offers the potential for preventive strategies designed to modify vein graft biology at the molecular level. This proposal seeks to develop a translational research program for addressing the critical obstacles currently limiting the application of genetic engineering to the problem of vein graft failure. A multidisciplinary approach, employing state of the art viral-based vector systems combined with molecular and functional analysis of gene expression in-vivo, will be employed. The program will support the development of the applicant, a vascular surgeon trained in genetic approaches, into an independent investigator capable of conducting preclinical and clinical evaluations of genetic interventions for vascular disease. The research and training will take place under the mentorship of a recognized leader in gene transfer technology, in an environment designed to streamline the development of such approaches by providing critical core technologies and expertise. The approach is divided into two distinct components. The first involves the rigorous evaluation of current and evolving viral vector systems for their application to vein grafting. Novel adenovirus, adeno-associated virus, pseudotyped retrovirus, and lentivirus vector systems will be examined for delivery efficiency, stability of gene expression, and host responses. The vein graft endothelium will constitute the primary target of these strategies. The effects of tissue specific (i.e. endothelial) versus viral promoters on transgene expression will be studied. The second phase will focus on the specific therapeutic goal of generating a thromboresistant vein graft surface. Gene constructs designed to increase natural anticoagulant (heparan sulfate synthesis, ADP hydrolysis, protein C activation) or thrombolytic (plasmin activation) functions of venous endothelium will be employed in animal models of vein grafting. The long term objective is to develop a safe, efficient, and effective protocol for intraoperative gene therapy that will engineer vein bypass grafts that are resistant to occlusion.